While dogs and mongoose can easily trace snakes by smell, when trained, one species eludes them. A piece of research from South Arica that used meerkats and dogs found the African puff adder, Bitis arietans to escape detection. It did this by means of what is assumed to be a reduction in volatile metabolites (with a molecular weight of <300.) The vapour pressure of molecules also comes into the equation, but it does seem that this snake may be unique among vertebrates in being able to adapt this particular stealth technique. Escape from predation is the major driver for the species as the mortality in wild populations is very high. Hunting ability must obviously be improved to some extent too.

Some interest lies in whether this useful ability is temporary or if it applies generally to the animal throughout its activity. Vipers sometimes have lower metabolic rates if they act as ambush predators. The same could be true of puff adders. Strangely, dogs could detect shed skins of puff adders although the snake always seems to defaecate when shedding, which could add some flavour! Other snakes can be expected to have this stealth ability, but this breakthrough explains how at least one particular species survives a high rate of predation.

The 42 listed predators of puff adders include eagles, buzzards, crows, hyena, genet cats and honey badgers, apart from the dogs and mustelids employed in the research. While visual camouflage is obviously useful against some of these, this chemical crypsis would act against the 15 predators listed that use olfactory methods of hunting. Remaining still, the puff adder seems to remain undetected compared to many other snakes in the same situation. This does not mean that related Bitis spp. and other snakes can’t manage the same trick. This is just the first, perhaps of several new examples of chemical crypsis.

Ashadee Kay Miller, Bryan Maritz, Shannon McKay, Xavier Glaudas and Graham J. Alexander of the Universities of the Witwatersrand and the Western Cape in South Africa published An ambusher's arsenal: chemical crypsis in the puff adder (Bitis arietans.) in The Proceedings of the Royal Society B. To vary the reptiles a bit, here is our summary of the recent taxonomic changes with pics of the giant (and social) skink and the tiniest chameleon. The relationship of vipers (including puff adders) to colubrids is also mentioned. .